ARTICULATIONS OF MAMMALIA /.V / .I/, / /rr/, I /,'. i _. 



animals ly MM- elasticity thry communicate to the bony walls of tlic cranium 

 or tare. In the adult, they may be said to bo null. 



CLASSIFICATION. There are four principal descriptions of ./// 

 1. When two wide bone* ooRBtpond bj metoa of denticulutiuiis fitting 

 into each other, the suture is named true or ilcntnlfd. I'Aample : tin; 

 :irtirulutii>ns uniting the three portions of the parietal bone. 2. If the 

 opposed borders of two bones in contact are widely bevelled, one inwards, 

 tin- other outwards, it forms a scaly or squamous suture. Example: tin- 

 Dftrieto-tempond articulations. 3. When the union of bones takes place 

 by plane or roughened surfaces, cut perpendicularly on their borders or 

 angles, this constitutes the hamtmtiu xiituri'. or milun' fy jvatOfOt&Um (or <y//i- 

 xitiim). Example: the occipito-temporal articulations. 4. The .><////////<. v/x, 

 / .s//////r, results from the reception of a bony plate into a groove 

 TIK. re or less deep in another bone. Example: the spheuo-frontal and 

 supermaxillo-nasal articulations. 



<:KNK;:AL CHARACTERS OF THE AMPHIARTHROSES OR 8YMPHYSES. 



ARTICULAR SURFACKS. They are frequently smooth, and formed almost 

 on the same model as the diarthrodial surfaces. They are covered by a 

 thin layer of cartilage, but instead of being smooth and polished, they are 

 more or less rugged, without, however, presenting the anfractuous disposition 

 of the majority of synarthrodial surfaces. 



MODES OF UNION. The organs which perform this office are : 1, The 

 iilu-o-cartilage which establishes continuity between the artictilar surfaces ; 

 2, Ki hi mn-shaped or peripheral ligaments. These latter do not differ from 

 the analogous bands attaching the diarthrodial articulations. With regard 

 to the nbro-cartilage, it is distinguished from the complementary discs of 

 same articulations by a less intimate mixture of the cartilaginous and 

 fibrous elements entering into its composition. The last may be sometimes 

 absent, as well as the peripheral bands ; and then the articulation only differs 

 from the synarthroses by the extent of motion it permits Occasionally the 

 iiiterarticular fibre-cartilages arc excavated byone or two little narrow cavities ; 

 but these are never lined by a synovial membrane like the diarthrodial 

 cavities. 



MOVEMENTS. The amphiarthroses only permit of a see-saw or swinging 

 movement, the extent of which depends on the thickness of the intermediate 

 iihro-cartilogo. 



CLASSIFICATION. Only one kind of amphiarthrosis is recognised, the 

 mt remarkable example of which is found in the articulations between the 

 bodies of the vertebrae. 



CHAPTER II. 



ARTICULATIONS OF MAMMALIA IN PAUTiriM.AR. 



1\ tin- special study of the articulations, the same onlirwill 1, followed 

 r the bones; the articulations of the spine will be first noticed, then 



those <>f the head, thorax, and anterior and posterior limbs. 



PiTptrntion. The preparation of the bones which have been disciiU'd 

 not lieen made the subject of any particular recommendation, IHXUSO 



it Miflices, in order to study them, to remove the soft parts b\ which 



